Light-emitting device having package structure with quantum dot material and manufacturing method thereof

ABSTRACT

A light-emitting device includes a light-emitting unit comprising a top surface and a first side surface; a light-transmitting layer covers the top surface and the first side surface; a wavelength conversion structure disposed on the light-transmitting layer; a protective layer covering the second side surface and the light-transmitting layer; and a reflective layer surrounding the protective layer. The wavelength conversion structure includes a wavelength conversion layer, a first barrier layer disposed on the wavelength conversion layer, a second barrier layer disposed under the wavelength conversion layer, the wavelength conversion layer, the first barrier layer, and the second barrier layer are collectively formed a second side surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending application Ser. No.16/280,465, filed on Feb. 20, 2019, for which priority is claimed under35 U.S.C. § 120; and this application claims priority of U.S.Provisional Application No. 62/632,732 filed on Feb. 20, 2018 under 35U.S.C. § 119(e); the entire contents of all of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to a light-emitting device, in particulara light-emitting device having a packaging structure with quantum dotmaterial.

Brief Description of the Related Art

The light-emitting diodes (LEDs) have the characteristics of low powerconsumption, long operating life, low heat generation, small volume,long operating life, impact resistance, small size, and fast response sothe LED is widely used in various fields where light-emitting componentsare required. For example, vehicles, home appliances, display screens,and lighting fixtures. The wavelength conversion material, such asphosphor, is a photoluminescent material and can absorb the first lightfrom the LED and convert the first light to a second light with adifferent spectrum from the first light.

Recently, the demand for display image quality is increasing, and thedevelopment of wide color gamut technology has become one of the mostimportant technological developments of displays. In general, if thefluorescent powder is used in the display, the NTSC is about 70˜80%. Ifthe quantum dot (QD) material is used in the display, the NTSC can bearound 100%.

Quantum dot material is one kind of wavelength conversion material.Different particle sizes of quantum dot material can emit light withdifferent wavelengths. In addition, the light converted by the quantumdot material can have a small Full Width at Half Maximum (FWHM). Thelight converted by the quantum dot material has a small Full Width atHalf Maximum and is similar to a monochromatic light. Hence, the quantumdot material is suitable for being used in the display and the amount oflight filtered by the color filter can be reduced.

SUMMARY OF THE INVENTION

The following description illustrates embodiments and together withdrawings to provide a further understanding of the disclosure describedabove.

A light-emitting device includes a light-emitting unit, alight-transmitting layer, a wavelength conversion structure, and areflective layer. The light-emitting unit includes a top surface and afirst side surface. The light-transmitting layer covers the top surfaceand the first side surface of the light-emitting unit. The wavelengthconversion structure is located on the light-transmitting layer. Thewavelength conversion structure includes a wavelength conversion layer,a first barrier layer located on the wavelength conversion layer, asecond barrier layer located under the wavelength conversion layer, anda third barrier layer covering side surfaces of the wavelengthconversion layer, the first barrier layer, and the second barrier layer.The reflective layer surrounds the light-transmitting layer and thewavelength conversion structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present disclosure.

FIG. 1B shows a top view of a light-emitting device in accordance withan embodiment of the present disclosure.

FIG. 1C shows a cross-sectional view of a light-emitting device inaccordance with another embodiment of the present disclosure.

FIGS. 2A˜2F show steps of manufacturing a wavelength conversionstructure in accordance with an embodiment of the present disclosure.

FIGS. 3A˜3F show steps of manufacturing a light-emitting device inaccordance with an embodiment of the present disclosure.

FIG. 4A shows a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present disclosure.

FIG. 4B shows a top view of a light-emitting device in accordance withan embodiment of the present disclosure.

FIGS. 5A˜5I show steps of manufacturing a light-emitting device inaccordance with an embodiment of the present disclosure.

FIG. 6A shows a cross-sectional view of a light-emitting device inaccordance with an embodiment of the present disclosure.

FIG. 6B shows a top view of a light-emitting device in accordance withan embodiment of the present disclosure.

FIGS. 7A˜7G show steps of manufacturing a light-emitting device inaccordance with an embodiment of the present disclosure.

FIG. 8A˜8C show cross-sectional views of a light-emitting device inaccordance with an embodiment of the present disclosure.

FIGS. 9A˜9B show steps of bonding the light-emitting device and thecircuit board in accordance with an embodiment of the presentdisclosure.

FIGS. 9C˜9D show steps of bonding the light-emitting device and thecircuit board in accordance with another embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drawings illustrate the embodiments of the application and, togetherwith the description, serve to illustrate the principles of theapplication. The same name or the same reference number given orappeared in different paragraphs or figures along the specificationshould has the same or equivalent meanings while it is once definedanywhere of the disclosure. The thickness or the shape of an element inthe specification can be expanded or narrowed.

FIG. 1A is a cross-sectional view of a light-emitting device 100 inaccordance with an embodiment of the present disclosure. Thelight-emitting device 100 includes a light-emitting unit 1, alight-transmitting layer 2, a reflective layer 3, a wavelengthconversion structure 5, and an adhesive layer 4. The light-emitting unit1 includes a top surface 101, two conductive electrodes 102A, 102Blocated on a bottom surface 103 opposite to the top surface 101, and aplurality of side surfaces 104. The light-emitting unit 1 can be a chiphaving a singular diode or a chip having a plurality of diodes foroperation under high-voltage. The top surface 101 of the light-emittingunit 1 is a light-emitting surface. The outermost surface of theconductive electrodes 102A, 102B does not exceed the side surface 104 ofthe light-emitting unit 1. In other words, the outermost surface of theconductive electrodes 102A, 102B is coplanar with or shrunk from theside surface 104 of the light-emitting unit 1. The light-transmittinglayer 2 surrounds the side surface 104 of the light-emitting unit 1 andcovers the top surface 101. The wavelength conversion structure 5 islocated above the light-transmitting layer 2 and is fixed to thelight-transmitting layer 2 through the adhesive layer 4. In other words,the adhesive layer 4 is located between the wavelength conversionstructure 5 and the light-transmitting layer 2, and the wavelengthconversion structure 5 is distant from the top surface 101 of thelight-emitting unit 1 by a distance greater than zero. The reflectivelayer 3 surrounds the light-transmitting layer 2, the light-emittingunit 1, the adhesive layer 4, and the wavelength conversion structure 5.The bottommost surface 303 of the reflective layer 3 is directly incontact with and substantially coplanar with the bottom surface 103 ofthe light-emitting unit 1. In other words, the bottom surface of thelight-transmitting layer 2 is not visible from appearance. In anotherembodiment, the light-transmitting layer 2 covers at least a portion ofthe bottom surface 103 of the light-emitting unit 1. The inner surfaceof the reflective layer 3 includes a first portion 301 and a secondportion 302 above the first portion 301. The first portion 301 isinclined to the bottommost surface 303 and directly covers thelight-transmitting layer 2. Hence, the width of the light-transmittinglayer 2 varies with the inclined surface of the first portion 301, andis gradually widened in a direction from the bottom surface 103 towardthe top surface 101 of the light-emitting unit 1. The second portion 302directly in contact with the adhesion layer 4 and the wavelengthconversion structure 5, and is substantially perpendicular to thebottommost surface 303 of the reflective layer 3. The outermost surface304 of the reflective layer 3 is substantially perpendicular to thebottommost surface 303. The topmost surface 305 of the reflective layer3 is a flat surface which is substantially perpendicular to theoutermost surface 304, and has a width that is not equal to and smallerthan that of the bottommost surface 303. The topmost surface 305 of thereflective layer 3 is substantially coplanar with the topmost surface505 of the wavelength conversion structure 5. In an embodiment, thetopmost surface 305 of the reflective layer 3 is not a flat surface andhas a recess or a protrusion. In another embodiment, the topmost surface305 of the reflective layer 3 is not coplanar with the topmost surface505 of the wavelength conversion structure 5 and can be higher or lowerthan the topmost surface 505 of the wavelength conversion structure 5.

The adhesive layer 4 and the top surface 101 of the light-emitting unit1 have a distance greater than 0. Therefore, the light-transmittinglayer 2 is located between the adhesive layer 4 and the top surface 101of the light-emitting unit 1. The maximum width of the adhesive layer 4is substantially equal to that of the wavelength conversion structure 5.In another embodiment, the maximum width of the adhesive layer 4 isgreater than or smaller than that of the wavelength conversion structure5. The thickness of the adhesive layer 4 can be thinner than that of thewavelength conversion structure 5. In an embodiment, the thickness ofthe adhesive layer 4 is less than 20 μm. The material of the adhesivelayer 4 can be a thermosetting resin or a photo-curable resin, such as asilicone resin.

The wavelength conversion structure 5 has a wavelength conversion layer501, a first barrier layer 502, a second barrier layer 503, and a thirdbarrier layer 504. The first barrier layer 502 and the second barrierlayer 503 can seal the top and bottom surfaces of the wavelengthconversion layer 501, and the third barrier layer 504 can seal the sidesurface of the wavelength conversion layer 501. Therefore, the outersurfaces of the wavelength conversion layer 501 is protected by barrierlayers and insulated from the water and oxygen come from outside, so asto improve the reliability of the wavelength conversion layer 501. Thefirst barrier layer 502 directly covers the top surface of thewavelength conversion layer 501, the second barrier layer 503 directlycovers the bottom surface of the wavelength conversion layer 501, andthe wavelength conversion layer 501 is sandwiched in between the firstbarrier layer 502 and the second barrier layer 503. The side surfaces ofthe first barrier layer 502, the wavelength conversion layer 501, andthe second barrier layer 503 can be substantially coplanar or be notcoplanar (not shown). The third barrier layer 504 covers the firstbarrier layer 502, the wavelength conversion layer 501, the side surfaceof the second barrier layer 503, and the bottom surface 506 of thesecond barrier layer 503. Therefore, the wavelength conversion layer 501is surrounded by the first barrier layer 502, the second barrier layer503, and the third barrier layer 504. The second barrier layer 503 issandwiched in between the wavelength conversion layer 501 and the thirdbarrier layer 504. The first barrier layer 502, the wavelengthconversion layer 501, and the second barrier layer 503 can havesubstantially the same width or different widths. The third barrierlayer 504 has an inner side surface 5041 directly contacting the sidesurfaces of the first barrier layer 502, the wavelength conversion layer501, and the second barrier layer 503. The inner surface 5041 issubstantially perpendicular to the topmost surface 505 of the wavelengthconversion structure 5 or contoured along the side surfaces of the firstbarrier layer 502, the wavelength conversion layer 501, and the secondbarrier layer 503.

The wavelength conversion layer 501 includes a quantum dot materialcontaining a matrix and quantum dot particles dispersed in the matrix.The material of the matrix can be a thermosetting resin or aphoto-curable resin, such as PMMA, epoxy resin, or silicone resin. Thematerial of the quantum dot particles can be semiconductor material andhas a particle diameter of less than or equal to 100 nm in general. Thesemiconductor material includes II-VI semiconductor compound, III-Vsemiconductor compound, IV-VI semiconductor compound, or combination ofthereof. The structure of the quantum dot particles can include a corethat used to emit light and a shell that used to cover the core. Thematerial of the core can be ZnS, ZnSe, ZnTe, ZnO, CsPbCl₃, CsPbBr₃,CsPbI₃, CdS, CdSe, CdTe, GaN, GaP, GaSe, GaSb, GaAs, AlN, AlP, AlAs,InP, InAs, Te, PbS, InSb, PbTe, PbSe, SbTe, ZnCdSe, ZnCdSeS, or CuInS.The material of the shell has to match the material of the core, forexample, the lattice constants of the core and shell need to match. Thematerial of the shell is preferred to have the lattice constant matcheswith that of the core, and can also form a high energy barrier region onthe periphery of the core to enhance the quantum yield. The structure ofthe shell can be a single layer, a multilayer, or a structure with agradual material composition ratio. In one embodiment, the core iscadmium selenide and the shell is a single layer of zinc sulfide. Inanother embodiment, the core includes cadmium selenide; the shellincludes an inner layer composed of cadmium and zinc, or composed ofsulfur and selenium, and an outer layer composed of zinc sulfide. Inanother embodiment, the core includes cadmium selenide (CdSe). The shellincludes an inner layer composed of cadmium sulfide (CdS), an outerlayer composed of zinc sulfide (ZnS), and a compositional transitionlayer disposed between the inner layer and the outer layer. Thecompositional transition layer can be composed ofZn_(0.25)Cd_(0.75)S/Zn_(0.5)Cd_(0.5)S/Zn_(0.75)Cd_(0.25)S, for example.The material composition ratio of the compositional transition layer isbetween that of the inner layer and that of the outer layer. In oneembodiment, the compositional transition layer is a layer composed of amixture of the materials of the outer layer and the inner layer.

The wavelength conversion layer 501 can include a wavelength conversionmaterial other than quantum dot particles. In one embodiment, thephosphor material can be mixed with the quantum dot particles in thematrix. For example, a phosphor material with fluoride which has theactivation center of manganese tetravalent and emits red light is mixedwith green quantum dot particles in a matrix. In another embodiment,other types of phosphor material and quantum dot particles are formed inlayers in the matrix. For example, a green light-emitting oxynitridephosphor layer is formed near the light-emitting unit 1, and red quantumdot particles and/or other color quantum dot particles cover on thephosphor layer. The wavelength conversion layer 501 can also includelight-scattering particles. In one embodiment, a plurality oflight-scattering particles is dispersed in the matrix. The routes of thelight from the light-emitting unit 1 and transmitting in the wavelengthconversion layer 501 can be increased by scattered by thelight-scattering particles. Therefore, the probability of that the lightfrom the light-emitting unit 1 and absorbed by the quantum dotmaterial/phosphor material is improved. The material of thelight-scattering particles can include cerium oxide or titanium oxideparticles.

The first barrier layer 502 and the second barrier layer 503 coveringthe top and bottom surfaces of the wavelength conversion layer 501 canhave similar or the same materials, such as PVDF (polyvinylidenedifluoride) or PET (polyethylene terephthalate). The heat deflectiontemperature (HDT) of PVDF is higher than PET and is about 200° C. Inaddition, the light transmittance of PVDF is greater than 92.5%. In anembodiment, the first barrier layer 502 and the second barrier layer 503include PVDF. During a reflowing step of the manufacturing process, thematerial properties of the first barrier layer 502 and the secondbarrier layer 503 are less destroyed due to high temperature. Afterreflowing step, the wavelength conversion layer 501 still has sufficientresistance to moisture and oxygen. The third barrier layer 504 caninclude a metal or an inorganic material. The metal can be Au, Al, Pt,Ni. The inorganic material can be SiO_(X), Al₂O₃, SiON, or SiN_(X).

The light-transmitting layer 2 can be silicone, epoxy, PI, BCB, PFCB,SUB, acrylic resin, PMMA, PET, PC, polyetherimide, fluorocarbon polymer,Al₂O₃, SINR, SOG. The material of the conductive electrodes 102A, 102Bcan be a metal such as Au, Ag, Cu, Cr, Al, Pt, Ni, Ti, Sn, an alloythereof, or a combination thereof.

The light-transmitting layer 2 does not contain wavelength conversionmaterial. In another embodiment, the light-transmitting layer 2 caninclude wavelength conversion material with a different emissionwavelength or/and different density than those of the wavelengthconversion layer 501. For example, the light-transmitting layer 2includes red phosphor, and the wavelength conversion layer 501 includesgreen quantum dot particles.

The reflective layer 3 can be a mixture of a matrix and a highreflectivity material. The matrix can be a silicone-based or epoxy-basedresin. The high reflectivity material can include titanium dioxide,Silicon dioxide, aluminum oxide, K₂TiO₃, ZrO₂, ZnS, ZnO, or MgO.

The light-emitting unit 1 is a semiconductor light-emitting elementwhich can emit the non-coherent/coherent light and includes a substrate,a first-type semiconductor layer, an active stack, and a second-typesemiconductor layer. The first-type semiconductor layer and thesecond-type semiconductor layer can be cladding layer or confinementlayer and provide electrons and holes respectively. The electrons andholes are recombined in the active stack to emit light. The first-typesemiconductor layer, the active stack, and the second-type semiconductorlayer can include a semiconductor material of III-V group, such asAl_(x)In_(y)Ga_((1-xy))N or Al_(x)In_(y)Ga_((1-xy))P, where 0≤x≤1;0≤y≤1; (x+y)≤1. Based on the material of the active stack, thelight-emitting unit 1 can emit a red light with a peak wavelength ordominant wavelength between 610 nm˜650 nm, a green light having a peakwavelength or dominant wavelength between 530 nm˜570 nm, a blue lighthaving a peak wavelength or dominant wavelength between 450 nm˜490 nm, aviolet light having a peak wavelength or dominant wavelength between400˜450 nm, or a ultra-violet light having a peak wavelength or dominantwavelength between 280˜400 nm. The substrate can be a growth substratefor epitaxially growing the first-type semiconductor layer, the activestack, and the second-type semiconductor layer in sequence thereon; orbe a carrier for the first-type semiconductor layer, the active stack,and the second-type semiconductor layer in sequence located thereonafter removing the growth substrate. The substrate can be made of amaterial, such as Ge, GaAs, InP, sapphire, SiC, Si, LiAlO₂, ZnO, GaN,AlN, metal, glass, composite, diamond, CVD diamond, Diamond-Like Carbon(DLC).

The wavelength conversion structure 5 is distant from the light-emittingunit 1 by a distance greater than 0, and the light-transmitting layer 2is located between the wavelength conversion structure 5 and thelight-emitting unit 1. The wavelength conversion structure 5 is notdirectly in contact with the light-emitting unit 1, and the heatproduced by the light-emitting unit 1 is not directly transmitted to thewavelength conversion structure 5. Therefore, the reliability of thewavelength conversion structure 5 is less affected by the risingtemperature due to the directly thermal conduction from thelight-emitting unit 1. A portion of the light is the absorbed/convertedlight which is emitted from the light-emitting unit 1 to the wavelengthconversion structure 5 and is absorbed/converted by the wavelengthconversion material in the wavelength conversion structure 5. Anotherportion of the light is non-absorbed/non-converted light which isemitted from the light-emitting unit 1 to the wavelength conversionstructure 5 and is not absorbed/converted by the wavelength conversionmaterial in the wavelength conversion structure 5. Theabsorbed/converted light and the non-absorbed/converted light arecompletely or partially mixed and exit the light-emitting device 100.

FIG. 1B is a top view of a light-emitting device 100 in accordance withan embodiment of the present disclosure. The wavelength conversionstructure 5 covers and locates on the light-emitting unit 1, and thereflective layer 3 surrounds the outer surfaces wavelength conversionstructure 5. In detail, the reflective layer 3 surrounds the thirdbarrier layer 504, and the third barrier layer 504 surrounds theperiphery of the first barrier layer 502. In the top view, the geometriccenters of the reflective layer 3, the third barrier layer 504, and thefirst barrier layer 502 locate at the similar position. FIG. 1B showsthat the light-emitting device 100 has a rectangular shape which is nota limitation of the present disclosure. In other embodiments, thelight-emitting device 100 can be other non-rectangular shapes, such astriangle, trapezoid, rhombus, parallelogram, square, circular, or otherpolygons. When the wavelength conversion material in the wavelengthconversion structure 5 is excited by the light from the light-emittingunit 1, the thermal energy is also produced by the wavelength conversionmaterial so the temperature of the wavelength conversion structure 5 isincreased and the reliability of the wavelength conversion structure 5is decreased. In one embodiment, the quantum dot particle existed in thewavelength conversion structure 5 can withstand a light energy densityof approximately 0.2 W/mm². If the intensity of the incident light istoo strong, the characteristics of the quantum dot particles, such asluminous efficiency and luminous intensity, may be deteriorated.Therefore, in order to reduce thermal energy generated by the wavelengthconversion material caused by wavelength conversion, the area of thewavelength conversion structure 5 is larger than the light-emittingsurface of the light-emitting unit 1 for reducing the light energydensity the wavelength conversion structure 5 can withstand. From thetop view, the top surface of the light-emitting unit 1 has an area A1,and the top surface of the wavelength conversion structure 5 has an areaA2, wherein A2>A1, and A2/A1 is in a certain range of values, forexample, 1.5<A2/A1<10.

The third barrier layer 504 can seal the side surfaces of the wavelengthconversion layer 501, so the third barrier layer 504 can alternativelyonly cover the side surfaces of the first barrier layer 502, thewavelength conversion layer 501, and the second barrier layer 503. Thebottom surface 506 of the second barrier layer 503 is not covered by thethird barrier layer 504, as shown in FIG. 1C. FIG. 1C is across-sectional view of a light-emitting device 110 in accordance to anembodiment of the present disclosure. The light-emitting device 110includes a light-emitting unit 1, a light-transmitting layer 2, areflective layer 3, a wavelength conversion structure 5, and an adhesivelayer 4. The wavelength conversion structure 5 includes a wavelengthconversion layer 501, a first barrier layer 502, a second barrier layer503, and a third barrier layer 504. The first barrier layer 502 directlycovers the top surface of the wavelength conversion layer 501, and thesecond barrier layer 503 directly covers the bottom surface of thewavelength conversion layer 501. The side surfaces of the first barrierlayer 502, the wavelength conversion layer 501, and the second barrierlayer 503 are substantially coplanar or not coplanar. The wavelengthconversion layer 501 is located between the first barrier layer 502 andthe second barrier layer 503. The third barrier layer 504 covers theside surfaces of the first barrier layer 502, the wavelength conversionlayer 501, and the second barrier layer 503. The bottom surface 506 ofthe second barrier layer 503 is not covered by the third barrier layer504 and is directly in contact with the adhesive layer 4. The details ofstructure and material of the light-emitting unit 1, thelight-transmitting layer 2, the reflective layer 3, the wavelengthconversion structure 5, and the adhesive layer 4 can be referred to thatof the aforementioned of light-emitting device 100.

FIGS. 2A˜2F show the steps of manufacturing a wavelength conversionstructure in accordance with an embodiment of the present disclosure.Referring to FIG. 2A, a wavelength conversion layer 501 having a firstbarrier layer 502 and a second barrier layer 503 is disposed on thefirst temporary carrier 61, wherein the first barrier layer 502 isdirectly in contact with the first temporary carrier 61 or adhered tothe first temporary carrier 61 by an adhesive layer (not shown). Next,referring to FIG. 2B, a plurality of aisles P1 is formed by cutting anddefines the sizes of the plurality of wavelength conversion structures.Referring to FIG. 2C, the third barrier layer 504 covers the sides ofthe first barrier layer 502, the wavelength conversion layer 501, andthe second barrier layer 503, and the upper surface of the secondbarrier layer 503, and fills in the aisle P1 by printing, coating,spraying, dispensing, or molding. Finally, referring to FIG. 2D, thethird barrier layer 504 in the aisle P1 is removed, and a plurality ofwavelength conversion structures 5 is formed on the first temporarycarrier 61. In another embodiment, the step of FIG. 2C is replaced byFIG. 2E, and the third barrier layer 504 only covers the sides of thefirst barrier layer 502, the wavelength conversion layer 501, and thesecond barrier layer 503, and fills in the aisle P1. The top surface ofthe second barrier layer 503 is not covered by the third barrier layer504. Finally, as shown in FIG. 2F, the third barrier layer 504 in theaisle P1 is removed, and a plurality of wavelength conversion structures5 is formed on the first temporary carrier 61. The material of the firsttemporary carrier 61 can be a thermal release tape, a UV tape, achemical release tape, a heat resistant tape, or a blue tape.

FIGS. 3A˜3F show the steps of manufacturing a light-emitting device inaccordance with an embodiment of the present disclosure. Here, themanufacturing steps only take the light-emitting device 100 as exemplaryhere. To make the light-emitting device 110, only the wavelengthconversion structure 5 needs to be replaced with the structure disclosedin FIG. 2F, and follows the same steps as described in FIGS. 3A˜3F.Referring to FIG. 3A, a second temporary carrier 62 with adhesion isprovided, and two conductive electrodes 102A, 102B of the plurality oflight-emitting units 1 are disposed on the second temporary carrier 62.The area between adjacent light-emitting units 1 is defined as an aisle,the light-transmitting layer 2 covers the top surface 101 of thelight-emitting unit 1 and fills in the aisle by printing, coating,spraying, dispensing, or molding. A planarization process, such as apolish process or blasting process, may be optionally performed toflatten the top surface of the light-transmitting layer 2. Subsequently,referring to FIG. 3B, an adhesive layer 4 is formed on thelight-transmitting layer 2. Referring to FIG. 3C, the structure of FIG.3B is inverted to align the light-emitting unit 1 with the wavelengthconversion structure 5 of FIG. 2D. The wavelength conversion structure 5of FIG. 2D is in contact with the adhesive layer 4 to fix the wavelengthconversion structure 5 under each of the light-emitting units 1. Thesecond temporary carrier 62 is removed to expose the conductiveelectrodes 102A, 102B. Next, referring to FIG. 3D, thelight-transmitting layer 2 and the adhesive layer 4 are diced to form acutting track C1 that has the upper portion which is wider and the lowerportion which is narrower in the cross-sectional view, and to expose theaisle P1 between the adjacent wavelength conversion structures 5. Inorder to form the cutting track C1 that has the upper portion which iswider and the lower portion which is narrower in the cross-sectionalview, it is preferable to use a blade having a similar outer shape toperform the cutting step. However, other cutting tools or themanufacturing processes which can form cutting track C1 with above shapeare not excluded in this application. Referring to FIG. 3E, reflectivelayer 3 is formed in the area between the cutting track C1 and the aisleP1 by printing, coating, spraying, dispensing, or molding. Subsequently,a planarization process, such as a polish process or blasting process,is performed to expose the conductive electrodes 102A, 102B. At thisstep, the reflective layer 3 can alternatively cover the bottom surface103 of the light-emitting unit 1 and filled between the conductiveelectrodes 102A, 102B. Finally, referring to FIG. 3F, the reflectivelayer 3 is diced and the first temporary carrier 61 is removed to form aplurality of light-emitting device. The method of removing the firsttemporary carrier 61 and the second temporary carrier 62 may be laserlift-off, heating separation, dissolution, or the like.

FIG. 4A is a cross-sectional view of a light-emitting device 200 inaccordance with an embodiment of the present disclosure. Thelight-emitting device 200 includes a light-emitting unit 1, alight-transmitting layer 2, a reflective layer 3, a wavelengthconversion structure 5, and a protective layer 7. The light-emittingunit 1 has a top surface 101, two conductive electrodes 102A, 102Blocated on the bottom surface 103 opposite to the top surface 101 of thelight-emitting unit 1, and a plurality of side surfaces 104. Thelight-emitting unit 1 can be a chip having a singular diode or a chiphaving a plurality of diodes for operation under high-voltage. The topsurface 101 of the light-emitting unit 1 is a light-emitting surface.The outermost surface of the conductive electrodes 102A, 102B does notexceed the side surface 104 of the light-emitting unit 1. In otherwords, the outermost surface of the conductive electrodes 102A, 102B iscoplanar with or shrunk from the side surface 104 of the light-emittingunit 1. The light-transmitting layer 2 surrounds the side surface 104 ofthe light-emitting unit 1 and covers the top surface 101. The wavelengthconversion structure 5 is located above the light-transmitting layer 2and directly in contact with the light-transmitting layer 2. Thewavelength conversion structure 5 is distant from the top surface 101 ofthe light-emitting unit 1 by a distance greater than zero. In anotherembodiment, similar to the light-emitting device 100, an adhesive layer(not shown) is between the wavelength conversion structure 5 and thelight-transmitting layer 2. The reflective layer 3 surrounds thelight-transmitting layer 2, the light-emitting unit 1, and thewavelength conversion structure 5. The bottommost surface 303 of thereflective layer 3 is directly in contact with and substantiallycoplanar with the bottom surface 103 of the light-emitting unit 1. Inother words, the bottom surface of the light-transmitting layer 2 is notvisible from appearance. In another embodiment, the light-transmittinglayer 2 covers at least a portion of the bottom surface 103 of thelight-emitting unit 1. The inner surface 306 of the reflective layer 3is an inclined surface which is inclined to the bottommost surface 303of the reflective layer 3. The outermost surface 304 of the reflectivelayer 3 is substantially perpendicular to the bottommost surface 303.

The protective layer 7 is formed on the inner surface 306 of thereflective layer 3, has a thickness, for example, larger than 10 μm andsmaller than 50 μm, and has an acute angle with respect to the topmostsurface 505 of the wavelength conversion structure 5. The protectivelayer 7 includes a first portion 701 and a second portion 702 locatedabove the first portion 701. The first portion 701 is located betweenthe light-transmitting layer 2 and the reflective layer 3 and directlycovers the side surface of the light-transmitting layer 2. The secondportion 702 is located between the wavelength conversion structure 5 andthe light-transmitting layer 2 and directly covers the side surface ofthe wavelength conversion structure 5. The protective layer 7 caninclude metal or inorganic material. The metal can be Au, Al, Pt, Ni.The inorganic material can include SiO_(X), Al₂O₃, SiON or SiN_(X).

The wavelength conversion structure 5 has a wavelength conversion layer501, a first barrier layer 502, and a second barrier layer 503. Thefirst barrier layer 502 directly covers the top surface of thewavelength conversion layer 501, the second barrier layer 503 directlycovers the bottom surface of the wavelength conversion layer 501, andthe wavelength conversion layer 501 is located between the first barrierlayer 502 and the second barrier layer 503. The side surfaces of thewavelength conversion layer 501, the first barrier layer 502, and thesecond barrier layer 503 collectively form an inclined surface which isdirectly covered by the second portion 702 of the protective layer 7.The first barrier layer 502 and the second barrier layer 503 can sealthe top and bottom surfaces of the wavelength conversion layer 501. Theprotective layer 7 can seal the side surface of the wavelengthconversion layer 501. Hence, the outer surfaces of the wavelengthconversion layer 501 are protected by the barrier layer and theprotective layer for isolating the external moisture and oxygen andimproving the reliability of the wavelength conversion layer 501. Thefirst barrier layer 502, the wavelength conversion layer 501, and thesecond barrier layer 503 collectively form a trapezoid that has theupper portion which is wider and the lower portion which is narrower inthe cross-sectional view. In detail, the width of the second barrierlayer 503 is smaller than that of the wavelength conversion layer 501,and the width of the wavelength conversion layer 501 is smaller thanthat of the first barrier layer 502. The topmost surface 505 of thewavelength conversion structure 5 is substantially coplanar with thetopmost surface 305 of the reflective layer 3 and the topmost surface703 of the protective layer 7.

The details of the material of the light-emitting unit 1, thelight-transmitting layer 2, the reflective layer 3, the first barrierlayer 502, the wavelength conversion layer 501, and the second barrierlayer 503 can be referred to the descriptions of the aforementionedparagraphs of light-emitting device 100 and are not repeated here.

FIG. 4B is a top view of a light-emitting device 200 in accordance withan embodiment of the present disclosure. The wavelength conversionstructure 5 covers and locates on the light-emitting unit 1, theprotective layer 7 surrounds the wavelength conversion structure 5, andthe reflective layer 3 surrounds the protective layer 7 (as shown inFIG. 4A). FIG. 4B shows that the light-emitting device 200 has arectangular shape which is not a limitation of the present disclosure.The light-emitting device 200 can be non-rectangular shapes, such astriangle, trapezoid, rhombus, parallelogram, square, circular, or otherpolygonal shapes. When the wavelength conversion material in thewavelength conversion structure 5 is excited by the light from thelight-emitting unit 1, the thermal energy is also produced by thewavelength conversion material so the temperature of the wavelengthconversion structure 5 is increased and the reliability of thewavelength conversion structure 5 is decreased. In one embodiment, thequantum dot particle existed in the wavelength conversion structure 5can withstand a light energy density of approximately 0.2 W/mm². If theintensity of the incident light is too strong, the characteristics ofthe quantum dot particles, such as luminous efficiency and luminousintensity, may be deteriorated. Therefore, in order to reduce thermalenergy generated by the wavelength conversion material due to wavelengthconversion, the area of the wavelength conversion structure 5 is largerthan the light-emitting surface of the light-emitting unit 1 forreducing the light energy density the wavelength conversion structure 5can withstand. From the top view, the top surface of the light-emittingunit 1 has an area A1, and the top surface of the wavelength conversionstructure 5 has an area A2, wherein A2>A1, and A2/A1 is in a certainrange of values, for example, 1.5<A2/A1<10.

FIGS. 5A˜5I show the steps of manufacturing a light-emitting device inaccordance with an embodiment of the present disclosure. As shown inFIG. 5A, the wavelength conversion layer 501 having the first barrierlayer 502 and the second barrier layer 503 is disposed on the firsttemporary carrier 61. The first barrier layer 502 is directly in contactwith the first temporary carrier 61 or adhered to the first temporarycarrier 61 by an adhesive layer (not shown). Next, as shown in FIG. 5B,the light-transmitting layer 2 is formed on the second barrier layer 503by printing, coating, spraying, dispensing, or molding. Referring toFIG. 5C, a second temporary carrier 62 with adhesion is provided, andtwo conductive electrodes 102A, 102B of the plurality of light-emittingunits 1 are disposed on the second temporary carrier 62. The areabetween adjacent light-emitting units 1 is defined as an aisle.Referring to FIG. 5D, the structure of FIG. 5C is inverted, and thelight-emitting unit 1 is buried in the light-transmitting layer 2 ofFIG. 5B such that the light-emitting unit 1 does not contact the secondbarrier layer 503. Referring to FIG. 5E, the second temporary carrier 62is removed to expose the conductive electrodes 102A, 102B. Next,referring to FIG. 5F, the light-transmitting layer 2, the first barrierlayer 502, the wavelength conversion layer 501, and the second barrierlayer 503 are diced to form a cutting track C1 that has the upperportion which is wider and the lower portion which is narrower in thecross-sectional view. In order to form the cutting track C1 that has theupper portion which is wider and the lower portion which is narrower inthe cross-sectional view, it is preferable to use a blade having asimilar outer shape to perform the cutting step. However, other cuttingtools or the manufacturing processes which can form cutting track C1with above shape are not excluded in this application. Referring to FIG.5G, in the cutting track C1, the protective layer 7 is formed on theinclined surface composed of the transparent layer 2, the first barrierlayer 502, the wavelength conversion layer 501, and the second barrierlayer 503 by atomic layer chemical vapor deposition (ALD),electroplating, or chemical plating. Subsequently, referring to FIG. 5H,reflective layer 3 is formed in the area between the cutting track C1and the aisle P1 by printing, coating, spraying, dispensing, or molding.Subsequently, a planarization process, such as a polish process orblasting process, is performed to expose the conductive electrodes 102A,102B. At this step, the reflective layer 3 can alternatively cover thebottom surface 103 of the light-emitting unit 1 and filled between theconductive electrodes 102A, 102B. Finally, referring to FIG. 5I, thereflective layer 3 is diced and the first temporary carrier 61 isremoved to form a plurality of light-emitting device.

FIG. 6A is a cross-sectional view of a light-emitting device 300 inaccordance with an embodiment of the present disclosure. Thelight-emitting element 300 includes a light-emitting unit 1, alight-transmitting layer 2, a reflective layer 3, a wavelengthconversion structure 5, and an adhesive layer 4. The light-emitting unit1 includes a top surface 101, two conductive electrodes 102A, 102B arelocated on a bottom surface 103 opposite to the top surface 101 of thelight-emitting unit 1, and a plurality of side surfaces 104. Thelight-transmitting layer 2 surrounds the side surface 104 of thelight-emitting unit 1 and covers the top surface 101. The wavelengthconversion structure 5 is located above the light-transmitting layer 2and is fixed to the light-transmitting layer 2 through the adhesivelayer 4. In other words, the adhesive layer 4 is located between thewavelength conversion structure 5 and the light-transmitting layer 2,and the wavelength conversion structure 5 is distant from the topsurface 101 of the light-emitting unit 1 by a distance greater thanzero. The reflective layer 3 surrounds the light-transmitting layer 2,the light-emitting unit 1, the adhesive layer 4, and the wavelengthconversion structure 5. The inner surface of the reflective layer 3includes a first portion 301, a second portion 302 above the firstportion 301, and a third portion 307 connecting the first portion 301and the second portion 302. The first portion 301 is perpendicular tothe bottommost surface 303 and directly covers the light-transmittinglayer 2. The second portion 302 directly contacts the wavelengthconversion structure 5 and is substantially perpendicular to thebottommost surface 303 of the reflective layer 3. The third portion 307is located between the first portion 301 and the second portion 302, hasan inclined surface, and is not parallel with the first portion 301 andthe second portion 302. In another embodiment, the third portion 307 isa curved surface. The outermost surface 304 of the reflective layer 3 issubstantially perpendicular to the bottommost surface 303. The distancebetween the first portion 301 of the inner surface of the reflectivelayer 3 and the outermost surface 304 is larger than the distancebetween the second portion 302 of the inner surface of the reflectivelayer 3 and the outermost surface 304. In other words, the width of theportion of the reflective layer 3 surrounding the light-transmittinglayer 2 is wider than the portion of the reflective layer 3 surroundingthe wavelength conversion structure 5. The topmost surface 305 of thereflective layer 3 is not a flat surface and has a recess. The end 3051of the topmost surface 305 contacting with the wavelength conversionstructure 5 is higher than the end 3052 where the topmost surface 305intersects the outermost surface 304. In another embodiment, the topmostsurface 305 of the reflective layer 3 is an inclined surface or a flatsurface. When the topmost surface 305 of the reflective layer 3 is aflat surface, the topmost surface 305 of the reflective layer 3 and thetopmost surface 505 of the wavelength conversion structure 5 arecoplanar. In another embodiment, the end 3051 where the topmost surface305 contacts the wavelength conversion structure is not in contact withthe topmost surface 505 of the wavelength conversion structure 5, andlower than the topmost surface 505 of the wavelength conversionstructure 5.

The adhesive layer 4 and the top surface 101 of the light-emitting unit1 have a distance greater than 0, and the light-transmitting layer 2 islocated between the adhesive layer 4 and the top surface 101 of thelight-emitting unit 1. The width of the top surface 401 of the adhesivelayer 4 is substantially equal to the width of the wavelength conversionstructure 5, and the width of the bottom surface 402 is substantiallyequal to the width of the light-transmitting layer 2. The width of thetop surface 401 of the adhesive layer 4 is not equal to the width of thebottom surface 402. When the adhesive layer 4 has a smaller thickness,the widths of the top surface and bottom surface of the adhesive layerhave less difference or are similar.

The wavelength conversion structure 5 has a wavelength conversion layer501, a first barrier layer 502, a second barrier layer 503, and a thirdbarrier layer 504. The first barrier layer 502 and the second barrierlayer 503 can seal the top and bottom surfaces of the wavelengthconversion layer 501, and the third barrier layer 504 can seal the sidesurface of the wavelength conversion layer 501. Therefore, the outersurfaces of the wavelength conversion layer 501 are protected by thebarrier layers for insulating from the water and oxygen come fromoutside, so as to improve the reliability of the wavelength conversionlayer 501. The first barrier layer 502 directly covers the top surfaceof the wavelength conversion layer 501, the second barrier layer 503directly covers the bottom surface of the wavelength conversion layer501, and the wavelength conversion layer 501 is sandwiched in betweenthe first barrier layer 502 and the second barrier layer 503. The sidesurfaces of the first barrier layer 502, the wavelength conversion layer501, and the second barrier layer 503 are substantially coplanar or notcoplanar (not shown). The third barrier layer 504 covers the firstbarrier layer 502, the wavelength conversion layer 501, the side surfaceof the second barrier layer 503, and the top surface 507 of the firstbarrier layer 502. Therefore, the wavelength conversion layer 501 issurrounded by the first barrier layer 502, the second barrier layer 503,and the third barrier layer 504. The first barrier layer 502 is locatedbetween the wavelength conversion layer 501 and the third barrier layer504. The second barrier layer 503 directly contacts the top surface 401of the adhesive layer 4.

The description of the material of the light-emitting unit 1, thelight-transmitting layer 2, the reflective layer 3, the adhesive layer4, the first barrier layer 502, the wavelength conversion layer 501, thesecond barrier layer 503, and the third barrier layer 504 can bereferred to the descriptions of the aforementioned paragraphs oflight-emitting device 100 and are not repeated here.

FIG. 6B is a top view of a light-emitting device 300 in accordance withan embodiment of the present disclosure. The wavelength conversionstructure 5 covers and locates on the light-emitting unit 1, and thereflective layer 3 surrounds the periphery of wavelength conversionstructure 5. In detail, in a top view, the reflective layer 3 surroundsthe periphery of the third barrier layer 504, and has a geometric centersimilar to that of the third barrier layer 504. When the wavelengthconversion material in the wavelength conversion structure 5 is excitedby the light from the light-emitting unit 1, the thermal energy is alsoproduced by the wavelength conversion material so the temperature of thewavelength conversion structure 5 is increased and the reliability ofthe wavelength conversion structure 5 is decreased. In one embodiment,the quantum dot particle existed in the wavelength conversion structure5 can withstand a light energy density of approximately 0.2 W/mm². Ifthe intensity of the incident light is too strong, the characteristicsof the quantum dot particles, such as luminous efficiency and luminousintensity, may be deteriorated. Therefore, in order to reduce thermalenergy generated by the wavelength conversion material due to wavelengthconversion, the area of the wavelength conversion structure 5 of thelight-emitting device 300 is larger than the light-emitting surface ofthe light-emitting unit 1 for reducing the light energy density thewavelength conversion structure 5 can withstand. From the top view, thetop surface of the light-emitting unit 1 has an area A1, and the topsurface of the wavelength conversion structure 5 has an area A2, whereinA2>A1, and A2/A1 is in a certain range of values, for example,1.5<A2/A1<10.

FIGS. 7A˜7G show the steps of manufacturing a light-emitting device inaccordance with an embodiment of the present disclosure. Referring toFIG. 7A, a second temporary carrier 62 with adhesion is provided, andtwo conductive electrodes 102A, 102B of the plurality of light-emittingunits 1 are disposed on the second temporary carrier 62. The areabetween adjacent light-emitting units 1 is defined as an aisle. Thelight-transmitting layer 2 covers the top surface 101 and the sidesurface 104 of the light-emitting unit 1 and fills in the aisle byprinting, coating, spraying, dispensing, or molding. A planarizationprocess, such as a polish process or a blasting process, may beoptionally performed to flatten the top surface of thelight-transmitting layer 2. Subsequently, referring to FIG. 7B, aportion of the light-transmitting layer 2 located in the aisle isremoved by dicing to form a cutting track C2. Referring to FIG. 7C, theadhesive layer 4 is formed above the light-transmitting layer 2.Referring to FIG. 7D, the wavelength conversion structure 5 of FIG. 2Dis inverted and disposed on the third temporary carrier 63. Then thefirst temporary carrier 61 is removed. Subsequently, referring to FIG.7E, the light-emitting unit 1 is aligned with the structure of FIG. 7D,and the wavelength conversion structure 5 is moved down to adhere to theadhesive layer 4. Hence, the wavelength conversion structure 5 is fixedto corresponding light-emitting units 1 and can cover one or more thanone light-emitting unit. Subsequently, the third temporary carrier 63 isremoved to expose the cutting track C2. Referring to FIG. 7F, thereflective layer 3 is filled in the cutting track C2 by printing,coating, spraying, dispensing, or molding. Therefore, the reflectivelayer 3 covers the side surfaces of the wavelength conversion structures5 and the light-transmitting layer 2. In this step, the filling heightof the reflective layer 3 does not exceed the wavelength conversionstructure 5, so the polishing process is not needed for exposing thewavelength conversion structure 5. On the other hand, if the fillingheight of the reflective layer 3 exceeds the wavelength conversionstructure 5, the step of reducing the height may be performed as neededso the height of the topmost surface of the reflective layer 3 mayexceed the topmost surface of the wavelength conversion structure 5.Finally, referring to FIG. 7G, the reflective layer 3 is diced and thesecond temporary carrier 62 is removed to form a plurality oflight-emitting device. The details of the material and the removingmethod of the third temporary carrier 63 are the same as those of thefirst temporary carrier 61 and the second temporary carrier 62, and canbe referred to the aforementioned related paragraphs.

The light-emitting unit 1 of the aforementioned light-emitting devices100, 110, 200, 300 can be a flip chip. In other words, the twoconductive electrodes 102A, 102B of the light-emitting unit 1 arelocated on the same side of the light-emitting unit 1. In otherembodiments, the light-emitting unit 1 can be replaced with a face-upchip as shown in FIGS. 8A˜8C. FIG. 8A is a cross-sectional view of alight-emitting device 400 in accordance with an embodiment of thepresent disclosure. The details of structures and materials of thereflective layer 3, the light-transmitting layer 2, the wavelengthconversion structure 5, and the adhesive layer 4 of the light-emittingdevice 400 are the same as those of the light-emitting device 300, andcan be referred to the aforementioned related paragraphs. Thelight-emitting unit 1 of the light-emitting device 300 is replaced withthe light-emitting unit 11 and a sub-mount 9 so as to form thelight-emitting device 400. The light-emitting unit 11 is disposed on thesub-mount 9. The sub-mount 9 includes a first conductive portion 91 anda second conductive portion 92 which are physically separated, and aninsulating portion 93 surrounding and connecting the first conductiveportion 91 and the second conductive portion 92. In an across-sectionalview, the width of the second conductive portion 92 is wider than thatof the first conductive portion 91. In a bottom view (not shown), theinsulating portion 93 surrounds the side surfaces of the firstconductive portion 91 and the second conductive portion 92 andoptionally forms a flat plane on the top and bottom surfaces of thefirst conductive portion 91 and the second conductive portion 92. Indetail, the top surface 911 of the first conductive portion 91 and thetop surface 921 of the second conductive portion 92 are not covered bythe insulating portion 93 and are coplanar with the top surface 931 ofthe insulating portion 93. The bottom surface 912 of the firstconductive portion 91 and the bottom surface 922 of the secondconductive portion 92 are not covered by the insulating portion 93 andare coplanar with the bottom surface 932 of the insulating portion 93.The bottom surface 113 of the light emitting unit 11 is fixed to thesecond conductive portion 92 of the sub-mount 9 by an adhesive layer,which is not shown and can be a silver glue, silicone resin, or epoxyresin. The width of the light-emitting unit 11 is smaller than that ofthe second conductive portion 92. The light-emitting unit 11 has a firstconductive electrode 112A and the second conductive electrode 112B whichare disposed on the top surface opposite to the bottom surface 113. Thefirst conductive electrode 112A is electrically connected to the firstconductive portion 91 by a conductive wire 81, and the second conductiveelectrode 112B is electrically connected to the second conductiveportion 92 by a conductive wire 82. The light-transmitting layer 2surrounds and covers the light-emitting unit 11, the first conductiveelectrode 112A, the second conductive electrode 112B, and the conductivewires 81, 82. The reflective layer 3 is directly in contact with theoutermost side of the sub-mount 9. In other words, the reflective layer3 is directly in contact with the insulating portion 93 of the sub-mount9. The bottommost surface 303 of the reflective layer 3 is coplanar withthe bottom surface 912 of the first conductive portion 91, the bottomsurface 922 of the second conductive portion 92, and the bottom surface932 of the insulating portion 93. The external power can be provided tothe light-emitting unit 11 through the first conductive portion 91 andthe second conductive portion 92 to turn on the light-emitting unit 11.In another embodiment (not shown), the reflective layer 3 is notdirectly in contact with the outermost side of the sub-mount 9. In otherwords, the light-transmitting layer 2 directly covers the outermost sideof the sub-mount 9.

The material of the first conductive portion 91 and the secondconductive portion 92 can be a metal such as Au, Ag, Cu, Cr, Al, Pt, Ni,Ti, Sn, an alloy thereof, or a combination thereof. The material of theinsulating portion 93 can be the same as that of the light-transmittinglayer 2 for fixing the first conductive portion 91 and the secondconductive portion 92. In another embodiment, the material of theinsulating portion 93 may be the same as that of the reflective layer 3to increase the light intensity of the light-emitting device 400.

In another embodiment, the light-emitting unit 11 is disposed on theinsulating layer of the sub-mount 9 as shown in FIG. 8B. FIG. 8B is across-sectional view of a light-emitting device 410 in accordance withan embodiment of the present disclosure. The structure of thelight-emitting device 410 is similar to that of the light-emittingdevice 400, but the structure of the sub-mount 9 is different from thatof the light-emitting device 400. The details of the structures andmaterials of the light-emitting unit 11, the reflective layer 3, thelight-transmitting layer 2, the wavelength conversion structure 5, andthe adhesive layer 4 of the light-emitting device 410 are the same asthose of the light-emitting device 400 and can be referred to theaforementioned related paragraphs. The sub-mount 9 includes a firstconductive portion 91 and a second conductive portion 92 which arephysically separated, and insulating portion 93 surrounding andconnecting the first conductive portion 91 and the second conductiveportion 92. The width of the second conductive portion 92 can be thesame as or different from the width of the first conductive portion 91.The insulating portion 93 includes a first portion 933 located on anouter side of the sub-mount 9 and surrounding and covering the outerside surfaces of the first conductive portion 91 and the secondconductive portion 92. The second portion 934 of the insulating portion93 is located between the first conductive portion 91 and the secondconductive portion 92 and covers the inner side surfaces of the firstconductive portion 91 and the second conductive portion 92. Theinsulating portion 93 form a common flat plane with the top and bottomsurfaces of the first conductive portion 91 and the second conductiveportion 92. The light-emitting unit 11 is located between the firstconductive portion 91 and the second conductive portion 92, and thebottom surface 113 of the light-emitting unit 11 is fixed to the secondportion of the insulating portion 93 through an adhesive layer (notshown). The reflective layer 3 is not directly in contact with the firstportion of the insulating portion 93, and the light-transmitting layer 2is located between the first portion of the insulating portion 93 andthe reflective layer 3. The bottom surfaces of the reflective layer 3,the light-transmitting layer 2, and the sub-mount 9 are coplanar. Inanother embodiment, the reflective layer 3 is directly in contact withthe first portion of the insulating layer 93.

In another embodiment, the first conductive portion 91 and the secondconductive portion 92 are surrounded and fixed by the light-transmittinglayer 2. As shown in FIG. 8C, a cross-sectional view of a light-emittingdevice 420 in accordance with an embodiment of the present disclosure isdisclosed. The details of the structures and materials of thelight-emitting unit 11, the reflective layer 3, the light-transmittinglayer 2, the wavelength conversion structure 5, and the adhesive layer 4of the light-emitting device 420 are the same as those of thelight-emitting device 400 and can be referred to the aforementionedrelated paragraphs. The bottom surface 113 of the light-emitting unit 11is fixed to the second conductive portion 92 through an adhesive layer(not shown). The width of the light-emitting unit 11 is smaller thanthat of the second conductive portion 92. The first conductive portion91 is physically separated from the second conductive portion 92, andthe width of the second conductive portion 92 is wider than that of thefirst conductive portion 91. The light-transmitting layer 2 surroundsthe side surfaces and the top surfaces of the first conductive portion91 and the second conductive portion 92 for fixing and supporting thefirst conductive portion 91 and the second conductive portion 92. Indetail, the light-transmitting layer 2 covers the first conductiveportion 91, the second conductive portion 92, the light-emitting unit11, and the conductive wires 81, 82. The reflective layer 3 is notdirectly in contact with the first conductive portion 91 and the secondconductive portion 92. The light-transmitting layer 2 is located betweenthe reflective layer 3 and the first conductive portion 91 and thesecond conductive portion 92.

In other embodiments, the light-emitting unit 1 of the light-emittingdevice 100, 110, and 200 can be replaced with the light-emitting unit11, the sub-mount 9, the first conductive portion 91, and the secondconductive portion 92 of FIGS. 8A˜8C.

FIGS. 9A˜9B show steps of bonding a light-emitting device to a circuitboard in accordance with an embodiment of the present disclosure.Referring to FIG. 9A, the light-emitting device 100 is taken as anexample. In other embodiments, the light-emitting device can be thelight-emitting devices 110, 200, 300, 400, 410, 420. The firstconductive electrode 102A and the second conductive electrode 102B facethe bonding pads 121A, 121B on the circuit board 12, respectively. Thepaste 13 is formed between the light-emitting device 100 and the circuitboard 12. Referring to FIG. 9A, before thermal curing, the paste 13includes an insulating material 132 and a plurality of conductiveparticles 131 dispersed in the insulating material 132. The method ofbonding the light-emitting device 100 includes a thermal curing step.During the curing process, the temperature is not over 170° C., theviscosity of the insulating material 132 is first decreased and thenraised, and the conductive particles 16052 are gathered in a regionwhich is between or around the first conductive electrode 102A and thebonding pad 121A and between or around the second conductive electrode102B and the bonding pad 122B. FIG. 9B shows the state after thermalcuring. The area covered by the paste 13 includes a conductive region 11and a non-conductive region 142. The conductive region 141 is locatedbetween the first conductive electrode 102A and the bonding pad 121A,and between the second conductive electrode 102B and the bonding pad121B. Except the conductive region 141, the other region covered by thepaste is the non-conductive region 142. As shown in FIG. 9A, before thethermal curing step, the average density of the conductive particles 131in the conductive region 141 is similar to that in the non-conductiveregion 142. As shown in FIG. 9B, after the thermal curing step, most ofthe conductive particles 131 are concentrated in the conductive region141. The average density of the conductive particles 131 in theconductive region 141 is larger than that in the non-conductive region142. In an embodiment, the conductive particles 131 in the conductiveregion 141 have an average density larger than 75%, or the conductiveregions 141 preferably without having the insulating material 132. Theaverage density of conductive particles 131 in non-conducting region 142is less than 40%, but not equal to zero. In other words, thenon-conduction region 142 contains a small amount of conductiveparticles 131 that are separated from each other. For example, theaverage density of the conductive particles 131 in the non-conductionregion 142 is between 0.1% and 40%, preferably between 2% and 10%. Theaverage density of the insulating material 132 in the non-conductingregion 142 is larger than 60%, preferably between 60% and 99.9%, andmore preferably between 90% and 98%. In one embodiment, thenon-conducting region 142 includes the conductive particles 131 with theaverage density of 10%˜40% and the insulating material 132 with theaverage density of 60%˜90%, and preferably the conductive particles 131with the average density of 20%˜30% and the insulating material 132 withthe average density of 70%˜80%. In another embodiment, thenon-conducting region 142 does not include conductive particles 131.

The paste 13 can be divided into a plurality of sub-portions (forexample, 3 to 10 sub-portions). The average density is defined as theaverage of the density of all or selected sub-portions. The size of thesub-portion can be adjusted depending on the size of the test sample ormeasurement method. For example, the sub-portion has a three-dimensionalshape or has a two-dimensional shape in a cross-sectional view. Thetwo-dimensional shape may be an octagon, a hexagon, a rectangle, atriangle, a circle, an ellipse, or a combination thereof. Thethree-dimensional shape can be a cylinder, a cube, a cuboid, or asphere. The density of the conductive particles 131 is measured bycalculating the number or occupation area observed from a selected viewof all the conductive particles 131 in a sub-portion (for example, 20×20μm²).

The conductive particles 131 can include a metal with a low meltingtemperature or an alloy with low liquidus melting temperature and have amelting temperature or liquidus melting temperature of less than 210° C.The metal can be an element, a compound, or an alloy, such as Bi, Sn,Ag, In, or an alloy thereof. In one embodiment, the melting temperatureor liquidus melting temperature of the metal or the alloy is less than170° C. The material of the alloy with the low liquidus meltingtemperature can be a Sn—In alloy or a Sn—Bi alloy. The insulatingmaterial 132 can be a thermosetting polymer such as epoxy, silicone,polymethyl methacrylate, and episulfide. The insulating material 132 canbe cured at a curing temperature. In an embodiment, the meltingtemperature of the conductive particles 131 is lower than the curingtemperature of the insulating material 132. As shown in FIG. 9A, beforethe thermal curing step, the size of the conductive particles 131 isdefined as the diameter of the conductive particles 131, which isbetween 1 μm and 20 μm, for example, 2 μm, 10 μm. The weight percentageratio of the conductive particles 131 to the paste 13 is between 30% and80%. In one embodiment, when the average size of the conductiveparticles 131 is approximately 2 μm, the weight percentage ratio of theconductive particles 131 to the paste 13 is between 30% and 70%. Inanother embodiment, when the average size of the conductive particles131 is approximately 10 μm, the weight percentage ratio of theconductive particles 131 to the paste 13 is between 40% and 80%. Theshortest distance between the first conductive electrode 120A and thesecond conductive electrode 102B is preferably more than twice theparticle size of the conductive particles 131.

In an embodiment, the insulating material 132 is pervious to light. Inanother embodiment, the insulating material 132 can optionally include alight-absorbing substance to make the insulating material shown as darkcolor, such as black, for increasing the contrast of the display whenthe light-emitting device is applied to a display. In anotherembodiment, the insulating material 132 can optionally include a highreflectivity material to make the insulating material shown as whitecolor to reflect the light from the light-emitting device and emittedtoward the circuit board for increasing the light intensity of thelight-emitting device. The light-absorbing substance can be carbon,titanium oxide, or dark pigment.

As shown in FIG. 9B, after thermal curing step, the conductive particleslocated in the conductive region 141 are aggregated into a bulk and be aconductive structure 133. The conductive structure 133 covers at leastone side surfaces of the first conductive electrode 102A, the secondconductive electrode 102B, and the bonding pads 121A, 121B. Theconductive structures 133 directly connect the first conductiveelectrode 102A, the second conductive electrode 102B, and the bondingpads 121A, 121B respectively to provide electrical conduction. Theexternal power can drive the light-emitting device 1600 through thebonding pads 121A, 121B, the conductive structure 133, the firstconductive electrode 102A, and the second conductive electrode 102B. Theinsulating material 132 surrounds the outer surfaces of the conductivestructure 133, the first conductive electrode 102A, the secondconductive electrode 102B, and the bonding pads 121A, 121B. Theconductive particles 131 in the non-conductive region 142 aredistributed discretely and covered by the insulating material 132.Therefore, the conducting current cannot pass through the non-conductiveregion 142. The insulating material 132 filled in the non-conductiveregion 142 can enhance the bonding strength between the light-emittingdevice 100 and the circuit board 12, can avoid the conductive materialfrom oxidation caused by exposing to the external environment, and alsocan prevent the conductive structure 133 from softening or melting dueto high temperature environment that may cause a short circuit problem.In a cross-sectional view, taking the corresponding first conductiveelectrode 102A and the bonding pad 121A as an example, the bottom end ofthe conductive structure 133 (the end contacting the bonding pad 121A)completely covers the top surface of the bonding pad 121A, and the topend of the conductive structure 133 (the end contacting the firstconductive electrode 1601) completely covers the bottom surface of thefirst conductive electrode 102A. The conductive structure 133 has anecking shape, and the outer side surface of the conductive structure133 has a surface of with a concave portion and a convex portion. Inanother embodiment, the outer side surface of the conductive structure133 is a convex arc shape, and the conductive structure 133 does nothave the neck structure. In another embodiment, the outer side surfaceof the conductive structure 133 is a flat surface.

As shown in FIG. 9B, the outermost surface 134 of the paste 13 has acurved shape and extends from the circuit board 12 to the outer sidesurface 1001 of the light-emitting device 100. The shape of the paste 13is changed after thermal curing step (compared to FIG. 9A), that is, thepaste 13 has a different shape between before and after the thermalcuring step. The paste 13 covers a portion of the outer side surface1001 of the light-emitting device 100. More specifically, after thermalcuring step, as shown in FIG. 9B, the outermost surface 134 of the paste13 has an angle θ with respect to the circuit board 12, and the angle θgradually increases along the direction of the outermost surface 134toward the outer side surface 1001 of the light-emitting device 100.

FIGS. 9C˜9D show steps of bonding a light-emitting device to a circuitboard 12 in accordance with an embodiment of the present disclosure.Referring to FIG. 9C, the light-emitting device 100 is taken as anexample. In other embodiments, the light-emitting device can be thelight-emitting devices 110, 200, 300, 400, 410, 420. The firstconductive electrode 102A and the second conductive electrode 102B facethe bonding pads 121A, 121B on the circuit board 12, respectively. Thesoldering material 14 is formed on the bonding pads 121A, 121B. Energy Lis supplied in the bonding area and locally heats the soldering material14. The energy L can be a laser such as infrared light or UV light.Thereafter, referring to FIG. 9D, the light-emitting device 100 ispressed down onto the melted soldering material 14, and thelight-emitting device 100 is bonded to the circuit board 12 by thesoldering material 14. Because the energy L only locally heats thesoldering material 14 without heating the light-emitting device 100, thereliability of the wavelength conversion structure 5 of thelight-emitting device 100 is less affected during heating process. Thesoldering material 14 can be Sn, Cu, Ag, Bi, In, Zn, Ti, or acombination thereof. In another embodiment, the soldering material 14can be an anisotropic conductive film (ACF) or a paste 13 which is shownin FIG. 9A˜9B and has a self-assembly function.

It will be apparent to those having ordinary skill in the art thatvarious modifications and variations can be made to the devices inaccordance with the present disclosure without departing from the scopeor spirit of the disclosure. In view of the foregoing, it is intendedthat the present disclosure covers modifications and variations of thisdisclosure provided they fall within the scope of the following claimsand their equivalents.

What is claimed is:
 1. A light-emitting device, comprising: alight-emitting unit comprising a top surface and a first side surface; alight-transmitting layer covers the top surface and the first sidesurface; a wavelength conversion structure disposed on thelight-transmitting layer, comprising a wavelength conversion layer, afirst barrier layer disposed on the wavelength conversion layer, asecond barrier layer disposed under the wavelength conversion layer, thewavelength conversion layer, the first barrier layer, and the secondbarrier layer are collectively formed a second side surface; and aprotective layer covering the second side surface and thelight-transmitting layer; and a reflective layer surrounding theprotective layer.
 2. The light-emitting device according to claim 1,wherein the protective layer comprises a first portion located betweenthe reflective layer and the light-transmitting layer.
 3. Thelight-emitting device according to claim 1, wherein the protective layercomprises a second portion located between the second side surface andthe reflective layer.
 4. The light-emitting device according to claim 1,wherein the wavelength conversion structure has a topmost surface andthe protective layer is inclined to the topmost surface of thewavelength conversion structure.
 5. The light-emitting device accordingto claim 1, further comprising an area ratio of the wavelengthconversion structure to the light-emitting unit in a range of 1.5˜10 ina top view.
 6. The light-emitting device according to claim 1, whereinthe second side surface is an inclined surface.
 7. The light-emittingdevice according to claim 1, wherein the protective layer comprisesmetal.
 8. The light-emitting device according to claim 1, wherein thesecond barrier layer is directly in contact with the light-transmittinglayer.
 9. The light-emitting device according to claim 1, whereinwavelength conversion structure is a trapezoid.
 10. The light-emittingdevice according to claim 1, wherein the wavelength conversion layercomprises the quantum dot material.